Only two short years ago, Citibank was worth $244 billion. Now, after its stock lost half of its value in just the past week, the bank is estimated to be worth $20.5 billion. What happened? The New York Times attempted to answer that question Saturday, and it pointed the finger at the usual suspects — conflicts of interest between those who were supposed to manage risk — and those who stood to benefit from making risky bets.

A lot of blame has sloshed around for the sub-prime meltdown, from greedy borrowers to greedy mortgage brokers to Alan Greenspan, but if you want the real culprit, it was the repeal of the Glass-Stegall Act. On November 12, 1999, the champagne must have been shooting from the walls at Citigroup, which had worked behind the scenes for over 30 years to get the act overturned. After recovering from their hangover, they and their banking buddies went on a sub-prime lending orgy. But what was Glass-Steagall and how did it use to protect us?